OK, trouvé pour la sortie tube... ça m'a l'air juste genial...
Le truc c'est que ... ça revient cher comme solution... surtout si on considère qu'une seul LL1684 coute 140$...
Edit: j'ai pensé à la LL1684 car elle était beaucoup recommandé dans le topic précédent... mais peut être qu'une paire LL1527XL (@ 84$ l'unité) serait plus raisonnable :D
http://www.diyaudio.com/forums/twisted- ... ost2791604
Joe Rasmussen a écrit :I know where you are coming from. But the Sabre DAC is
different from any other DAC, not just that it can be used in both modes - but arguably sounds best in Current mode IMO.
If you go back through the posts, see the ones that discusses the lighter tonal balance of the Sabre DAC is Voltage mode.
If you want to use Voltage, then transformer is the way to go. Many have heard me say that many times over, that with a
differential voltage output where any DC offset will not be seen by the Primary of the transformer. But the Sabre DAC is
not a conventional Voltage DAC.
The Sabre DAC has a much higher output Z than is usual for a Voltage DAC and hence there is reason to point to it as the cause of the light tonal balance when used as such. We need to reduce that Z and also force the DAC into current.
So, Voltage mode, use:
The two resistors force the Sabre DAC into 3.14mA current offset while reducing offset voltage from 1.65V to about 1V. The output will be 1.3V RMS.
But
how could this be applied to using Tubes
and Current mode.
Pretty much all the post-DAC Tube designs I have seen avoid full-on Current mode. But with the Sabre DAC there
is and opportunity if employing above suggestion repeated here:
We can force the Sabre DAC into Current mode by pulling it virtually down to
0V DC and then get an offset current of 8mA. Using the same 1:1 transformer, it now opens up the way to use Current mode with Tubes.
So the above example shows how it can be done.
The point is that the Sabre DAC has flexibilities in the way that no other DAC has and using it in Plain Vanilla Voltage mode can be avoided as IMO it gives worst performance.
Cheers, Joe R.
Edit2... j'ai une idée encore plus tordu... quitte à se faire chier avec une topologie "sans opamp"... Je me suis dit, idéalement, en sortie de tube, il faut quand même un buffer pour driver du casque (car oui, toutes mes tergiversation sont faite pour à la fin, driver du casque, et le tout en balanced!)...
et la je me suis souvenu du fameux
bakoon et de sa topologie en current feedback amplifier...
et j'ai ressortie du chapeau ... le Sjostrom QRV08 ! et oui, cette monstreuse bête est une topologie en current feedback, avec un gain de 4 par defaut...
http://sjostromaudio.com/pages/index.ph ... imitstart=
ça donne une topologie du genre
Dac à base ES9018 => LL1584XL => 2 kit de gain linestage type Aikido ? => QRV08
